A nameless Sir Humphrey was busy working various rooms in New Delhi earlier today, trying to convince a largely unimpressed group of journalists and other hangers-on that Rahul Gandhi hadn’t snubbed David Cameron. He is, I’m afraid, fighting a losing battle: everyone of influence there confirms that a trade trip to India without meeting the shoe-in next Prime Minister is akin to visiting Hyannis Port without meeting a single Kennedy.

Although his mother Sonia Gandhi seems to have been genuinely engaged in wrestling with an emergency (she also missed a vital Parliamentary ceremony earlier in the week), Rahul’s decision to get on a plane and visit London for no reason was a very obvious snub. Writing in The Spectator earlier this week, Tory MP Jo Johnson had written that Rahul was ‘the preeminent figure with whom to establish a rapport’.

The truth is that Rahul Gandhi is (by image at least) a radical politician who has allied himself very closely with India’s young and poor, even saying openly that he would like to see an end to the caste system. He is a close friend of David Miliband, with whom he speaks and corresponds on a regular basis. Allegedly, the youngest Gandhi was bitterly disappointed when Labour lost the UK election: he met Cameron once in 2006 and didn’t take to him. Plus, as a rich Old Etonian, The British PM is the antithesis of a Britain he seems to despise. Rahul is on the record as saying that one thing above all making him proud of his heritage is that “the Gandhis kicked the British out of India”.

In the short term, however, my information is that the FCO made a huge gaffe by spending more time firming up a meeting with existing Indian Prime Minister Manmohan Singh. Singh is seen by most as yesterday’s man, and has been under pressure to name his retirement date so that Rahul can take over the reins. There is a history of enmity between Singh and Sonia Gandhi similar to that between Brown and Blair – both deny it, but everyone knows about it. Equally, it is alleged that Rahul finds the Indian PM patronising, and Singh in turn calls Gandhi “a playboy” in private.

Just two months ago – in a thinly veiled reference to Rahul’s love of speed machines – Manmohan Singh told a press conference, “Rahul is very qualified to hold a cabinet post. I have discussed it with him on a number of occasions. He has always been reluctant to give a positive answer. I sometimes feel that young people should take over. When Congress Party makes that judgement, I will be very happy. I have been given a work and it is incomplete yet; and till I complete it, there is no question of my retirement.”

A carefully phrased endorsement with little or nothing ringing about it. Yet another sign that the FCO seems to have missed….and what a chance to miss: this is Britain’s biggest State visit to India since Independence 63 years ago.

A junior member of the Tory Right was less than pleased with the trip in general and Rahul Gandhi’s behaviour in particular. He told the Slog at lunchtime (BST) today:

“There have been any number of curious incidents during this selling trip. Here is a country from whom we have accepted hundreds of thousands of immigrants, yet they demand that trade deals be dependent on more of that. We give a billion Pounds in aid to India every year, and yet the Gandhi family goes out of its way to make us feel unwelcome. Our Prime Minister declares himself willing to engage in a special relationship, and they more or less tell him to piss off. It’s not very edifiying. Cameron has been made to look silly.”